Archives de catégorie : Informatique

You installed Ubuntu on your Windows 10 through App Store ? Great ! But if you have a good memory, you know you type your user password. This one is needed for every single « sudo » instruction. Do you want to change this password without knowing the old one ? It’s very easy. No need to follow all the (very long) tutorial on the net with cryptic Windows command. Just go to this folder :

I have a server on a LAN that need to send emails. Of course, this server has access to the internet through NAT, but for emails it is a bit more difficult : nowadays, email servers are checking many things when receiving emails : reverse, ‘from’ field, etc. and you may not have access to this kind of tuning for the internet IP address used with your NAT. So I needed to configure a relayhost, with direct access to the internet, that would accept my incoming email and relay it through normal channels. But I don’t want this server to be an open relay, so I have to setup authentication between them.

Today I will talk about auditd, a very powerfull tool to debug anything you need in a linux platform. In this very case, I had a problem with a mail server using all IO available. ‘iostat’ command told me it was reads ops that saturate it. A mail server has many process, so using « strace » is not helpful here. I choose to use auditd.

If you also have this bug, fix is very easy : you need to remount the filesystem with « inode64 » option. This is because XFS, by default, only use the first terabyte of data to store inodes. If you create many files, this limit is reached. By adding the mount option ‘inode64’, you give XFS permission to use the whole device to create inodes.

Only drawback is bugs with very old softwares, especially over NFS. This is really a rare situation.